Numerical Optimization of Burner Deflection Angle at Half Load for a 660 MW Tangentially Fired Boiler

Abstract

China established a coal power capacity payment mechanism to allow coal power to play a fundamental supporting and regulating role. It is difficult to generate peak power for long periods. The effects of variation in over-fire air ratio and burner deflection angle were investigated to optimize combustion conditions at half load. This simulation is based on field data from a new 660 MW tangentially fired boiler. The results indicate that when the over-fire air ratio increased from 17.6% to 27.6%, the NOx concentration decreased by about 45.1% in the burnout zone. The concentration decreased from 284 mg/m3 to 156 mg/m3. However, a large eddy formed in the top zone affected the flow field. The heat transfer at the horizontal flue was affected. The flow field structure can be optimized by moderately adjusting the deflection angle (−5°) of the burner. A further increase in the deflection angles (−10° and −15°) reduced NOx by about 10%. It affected the adequate combustion of pulverized coal and the flow field at the top zone. Considering the overall combustion conditions, it is recommended that the burner be offset downward at a small angle.